Blockchain smart contracts are a new and exciting technology, As such, a significant amount of effort should be made to secure a smart contract.

After developing numerous smart contracts, I’ve decided to share my experience on common pitfalls that might have major security implications, and suggest how to avoid them.
The first part is about dealing with race conditions.

When you call an external contract, It may:
• Take over control flow
• Make changes to your data (When you didn’t expect it!)
Handling these difficult-to-anticipate situations was part of DAO’s bugs.

1. Reentry

Calling a function repeatedly, before the first invocation…